Bacterialogic, immunologic, radiographic and genetic studies were carried out on 76 randomly selected male Sri Lanka tea laborers from three subpopulations with rapidly progressing, moderately progressing, and non-progressing periodontitis. The specific aims of these studies will compare the presence and levels of selected putative periodontal pathogens, peripheral blood antibody titers, and evaluate the genetic determinants in the three distinct populations. In addition, tea laborers between the ages of 14-25 have been screened for a prospective study of the prevention of periodontal disease. Two master data sets for Norwegian Surveys 1-5 were built in SAS during this period. Data bases for the Norwegian Study are: LOE.NOR.AVO (All valid observations LOE.NOR.IAS in all surveys.) Two subpopulations were identified based on interproximal loss of attachment: (1) 42% with moderate disease and (2) 58% of the study group with loss of attachment not exceeding 2mm on any mesial surface at any survey. Preliminary studies have determined the mean number of years to the onset of the loss of connective tissue related to the severity of inflammation and calculus deposition in both the Sri Lankan and Norwegian study groups. Future investigations will continue to focus on the stability of the gingival lesion, and factors which may influence the continuity or discontinuity of periodontitis.